There is a multitude of different pressure and/or temperature balanced mixing valves on the market today, such valves being primarily used in residential or commercial installations for showers or sinks. Such valves have a single control handle, the movement of which determines the water flow rate and the temperature of the water exiting the valve. Typically, the valve installation will have a valve handle that is rotatable to control the water temperature and that is pulled or pushed relative to the valve housing to control the flow rate. Commonly owned Canadian Patent No. 1,050,853 issued on Mar. 20, 1979 presents a typical pressure balanced shower valve.
Valves of the above type are mounted behind a wall of a shower installation and include a pair of inlet ports, one for the hot water and one for the cold water. These inlets ports are usually situated on opposite sides of the valve housing. A single outlet port for water of the desired temperature and pressure is provided and is connectable to the shower head itself, which projects into the shower stall. A control stem projects from the valve housing into the shower stall and is connected to the valve handle. A replaceable cartridge within the valve housing accepts the hot and cold water and mixes it in the correct proportions, under control of the handle and feeds the mixed water to the outlet port.
When these single handle pressure balance valves are installed in commercial buildings such as hotels there can be a problem when a valve must be repaired, since the hot and cold water supplies must be shut off before repairs can be effected. Very often there is only a master control valve for the hot and cold water supplies within the building and when they are shut off there is no flow to the entire building. If only one valve needs to be repaired all other units must suffer while the broken valve is fixed. Even if there are shut off valves within the unit, they are often relatively inaccessible and they may be frozen open if they have not been used for a long time. There is therefore a need to have a mechanism for shutting off the hot and cold water supplies to a pressure balanced mixing valve in a quick and reliable manner, which mechanism should be simple, effective and unobtrusive.